(Photo: courtesy of Merlin Crossley, Melbourne, Victoria)

The body surface has a rough appearance. Individual caterpillars vary in colour from orange to red-brown. Abdominal segments two, three, and eight have small paired dorsal horns. The first pair of ventral prolegs is absent and the second and third pairs are reduced in size, and do not appear to clasp the stem. The anal prolegs are extended sideways, giving the anal segment a forked appearance. Some forms are plain brown, and some have a set of four narrow black bands around the body.

(Photo: courtesy of Cathy Byrne)

During the day, the caterpillars either stretch out and press against a stem, or they loop the front of the body into a circle so that the head and thorax lie on top of the abdomen. In this position, the caterpillar looks as if it has tied itself into a knot. We have seen this unusual posture in only one other species, (curiously: in a totally different family) namely Ischyja ebusa. The caterpillar grows to a length of about 4 cms.

(Photo: courtesy of Merlin Crossley, Melbourne, Victoria)

In Melbourne, pupation took place in early August, and the adlut moths emerged some seven months later in February the following year.

male
(Photo: courtesy of Cathy Byrne)

The adult male moth has grey forewings with black zizag transverse stripes. The hindwings and the undersurfaces of all four wings are silver with a broad black band along the margin. The wingspan of the male is about 3.5 cms.

female
(Photo: courtesy of Marilyn Hewish, Moths of Victoria: Part 5)

The female moth is similar except the dark basal line on each forewing is less jagged. The wingspan of the female is about 4 cms.

male
(Photo: courtesy of Marilyn Hewish, Moths of Victoria: Part 5)

The species occurs in:

(Photo: courtesy of Merlin Crossley, Melbourne, Victoria)

Females captured in in April in Melbourne deposited neat rows of eggs along the edges of leaves. The eggs hatched after about 18 days.

eggs mmagnified
(Photo: courtesy of Cathy Byrne)

DNA studies have shown that there are eight unnamed species in the genus Stibaroma in addition to the two listed here.

Further reading :

Edward Guest,
A classified list of Geometrina found around Balhannah, with notes on species,
Transactions of the Royal Society of South Australia,
Volume 9 (1887), p. 140, No. 22.

Marilyn Hewish,
Moths of Victoria: Part 5
Satin Moths and Allies - GEOMETROIDEA (A),
Entomological Society of Victoria, 2014, pp. 16-17.

Cathy Byrne,
Characterisation of the Australian Nacophorini and a Phylogeny for the Geometridae from Molecular and Morphological Data,
Ph.D. thesis, University of Tasmania, 2003.

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(updated 27 May 2010, 28 November 2014, 16 December 2020, 30 April 2021)